Fourth generation (4G) cellular networks employing newer radio access technology (RAT) systems that implement the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and LTE Advanced (LTE-A) standards are rapidly being developed and deployed within the United States and abroad. LTE-A brings with it the aggregation of multiple component carriers (CCs) to enable this wireless communications standard to meet the bandwidth requirements of multi-carrier systems that cumulatively achieve data rates not possible by predecessor LTE versions. In 3GPP LTE, an LTE carrier is limited to communicating at various designated system bandwidths ranging from 1.4 MHz up to 20 MHz.
For LTE-A carriers, interoperability with LTE carriers dictates that an LTE-A carrier must employ a system bandwidth equivalent to its LTE counterparts. As such, the peak single-carrier LTE-A system bandwidth is capped at 20 MHz for inter-LTE RAT compatibility. However, in a multiple CC scenario, an aggregated set of LTE-A carriers may be able to achieve cumulative bandwidths of up to 100 MHz within various allocated spectrum bands. Generally, user equipment (UEs) operating within an LTE cell or an LTE-A cell employ operating bandwidths to mirror a serving cell's system bandwidth; this implementation ensures that sufficient radio resources are allocated to support different UE data type communications.
For instance, when a UE attempts to decode control information of various wide-band communication channels, such as the physical downlink control channel (PDCCH), the UE will typically employ an operating bandwidth of 10 MHz or 20 MHz to decode the PDCCH. Control information carried in the PDCCH is referred to as downlink control information (DCI). The DCI may include downlink (DL) assignment (e.g., resource allocations of the physical downlink shared channel or PDSCH), as well as, uplink (UL) resource grant information (e.g., resource allocations of the physical uplink shared channel or PUSCH), transmit power control information, etc. An LTE or LTE-A base station (i.e., an eNodeB) may designate a PDCCH format according to its DCI information, which can be directed at a single UE or to multiple UEs residing within the same cell. For instance, PDCCH DCI may be associated with a cell radio network temporary identifier (C-RNTI) directed at a single UE, or alternatively, PDCCH DCI may be associated with a paging RNTI (P-RNTI) or a system information RNTI (SI-RNTI) directed at a group of UEs located within the same cell.
Unfortunately, LTE carriers can require UEs to perform blind decoding of the PDCCH to attempt to locate DCI control information intended for a specific UE and/or for a group of UEs operating within the same network cell (e.g., as indicated by an RNTI designation). For example, a UE may be required to perform blind decoding in scenarios where the UE is not aware of a carrier's PDCCH control channel structure, associated with the quantity of PDCCH control channels and the number of control channel elements (CCEs) to which each control channel is mapped. In these situations, a UE that performs blind decoding to attempt to locate the PDCCH and acquire its DCI are faced with the problem of exhausting UE device resources (e.g., battery power, processor and memory resources, etc.) to perform unnecessary PDCCH searches, particularly when a UE is engaged in low-bandwidth, periodic communications, such as voice over LTE (VoLTE) communications that could otherwise allow a UE to operate in a power conservation mode.
Further, as is understood by those skilled in the art, the PDCCH is a wide-band communication channel that occupies the entire system bandwidth. As such, when a UE decodes the PDCCH for control information that has a relatively low resource block requirement, communication resources may be wasted. In this regard, it would be beneficial for a UE to be able to employ its radio frequency (RF) filter to decode a narrow-band channel communication channel (e.g., the PDSCH) for control information. In this manner, an RF filter can be configured to match the bandwidth of narrow-band channel, as opposed to an entire system bandwidth.
Accordingly, there exists a need for solutions that can conserve local UE device resources and reduce network signaling required when a UE attempts to monitor DCI information to acquire DL resource assignments and UL resource grants.